| Document and Entity Information | Oct. 23, 2019 |
| Cover [Abstract] | |
| Amendment Flag | false |
| Entity Central Index Key | 0001512673 |
| Document Type | 8-K |
| Document Period End Date | Oct. 23, 2019 |
| Entity Registrant Name | Square, Inc. |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-37622 |
| Entity Tax Identification Number | 80-0429876 |
| Entity Address, Address Line One | 1455 Market Street |
| Entity Address, Address Line Two | Suite 600 |
| Entity Address, City or Town | San Francisco |
| Entity Address, State or Province | CA |
| Entity Address, Postal Zip Code | 94103 |
| City Area Code | (415) |
| Local Phone Number | 375-3176 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Class A common stock, $0.0000001 par value per share |
| Trading Symbol | SQ |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
